The function and utility of graft copolymers become clear when dealing U.S. Pat. No. 6,723,775, to Lau et al., which patent is incorporated herein by reference. Graft copolymers relate to a polymeric backbone having side chains of a different property or composition chemically attached thereto. Such polymers have very desirable film qualities. They can also be used to affect the structural qualities of other polymers in a desired fashion. Many uses of sodium poly(aspartate) to make a resulting graft copolymer are known, but they are inefficient for making intermediate products.
One known process uses the condensation method to make copolymers of sodium polyaspartic acid. They start the reaction with the use of L-Aspartic acid and other acids to terminate the polymerization process. In this case, because of the involvement of a second acid, it becomes a final product. It is suitable for use in forming copolymers or comb-graft copolymer only when the second acid contains a hydroxyl (—OH) terminated group).
Other processes using sodium poly(aspartate) form aqueous emulsion polymers and use at least one metal promoter complex, which greatly complicates the process. Other sodium poly(aspartate) uses are to form siloxane polymers, with a different redox system.
It is very desirable to solve the problems of these processes and achieve a more useful product.